Variable pitch propeller



J. E. ANDERSON VARIABLE PITCH PROPELLER Dec. 112, 1950 5 Sheets-Sheet 1 Filed Feb. 4, 1943 I VENTORS LTD Eiz zder'san ATTORNEY Dec. 12, 1950 J. E. ANDERSON VARIABLE PITCH 'PROPELLER Filed Feb. 4,

5 SheetsPSheet 2 luanEii jgIfgin arm 54 Q I I y Q I a) ATTORNEY Dec. m, 1950 J. E. ANDERSON 2,533,415

VARIABLE PITCH PROPELLER Filed Feb. 4, 1945 5 Sheets-Sheet 3 Deco 112, 1950 J. E. ANDERSON I VARIABLE PITCH PROPELLER 5 Sheets-Sheet 4 Filed Feb. 4, 1943 ENTORS EP5DI1 ATTORNEY Mam , LMHE Dec. 12, 1950 E. ANDERSON VARIABLE PITCH PROPELLER 5 SheetsSheet 5 Filed Feb. 4, 1943 away INVENTORS J5 5 9 5 2 m of Mad ATTORNEY Patented Dec. 12, 1950 UNITED STATES PATENT OFFICE VARIABLE PITCH PROPELLER John E. Anderson, Portland, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application February 4, 1943, Serial No. 474,638

12 Claims. (Cl. 170-16033) This invention relates to improvements in hydro-controllable aeronautical propellers and has particular reference to an improved hydraulic motor for changing the propeller pitch.

An object resides in the provision ofamotor in the base of a blade having torque resisting means connecting the motor with the hub.

An additional object resides in the provision of improved means for obtaining a desired preloading on the blade retaining bearings.

Other objects and advantages will be more particularly pointed out hereinafter or will become apparent as the description proceeds.

In the accompanying drawings, in which like reference numerals are utilized to designate similar parts throughout, there is illustrated a suitable mechanical embodiment for the purpose of disclosing the invention.

Fig. 1 is a sectional view through a propeller hub, showing a pitch changing motor constructed according to the invention, and diarammatically illustrating a hydraulic system for operating the motors.

Fig. 2 is a transverse sectional view on the line 2-2 of Fig. 1.

Fig. 3 is a sectional view of a fragmentary portion of the propeller taken on the line 3-3 of Fig. 1 and showing in detail the wedge construction for preloading the blade retaining bearings.

Fig. 4 is a transverse sectional view on the line 4-4 of Fig. l'particularly illustrating some of the connections between the fluid motors and the hub-includedportion of the hydraulic system.

Fig. 5 is a transverse sectional view on the line 5-5 of Fig. 1 showing details of one of the hydraulic motors.

Fig. 6 is a bottom view of a propeller blade with a hydraulic motor constructed according to the invention assembled therein.

Fig. 7 is a front elevational view, similar to Fig. 2, of the center portion of a propeller constructed according to the invention, a portion being broken away and shown in section to illustrate a somewhat modified form of motor and blade retention means.

The propeller has a hub l0 mounted on shaft l2 of the engine l4. The hub is splined to shaft i2 as indicated at i6, andis held in operative position on the shaft by cones i8 and 20, and nut 22 threaded onto shaft i2. The hub has bladeretaining sockets 24, 26 and 28 (Fig. 2) which receive blades 30, 32 and 34. The blades are retained in the sockets by stacked thrust ball bearings, as indicated at 36. 38. 40 and 42, in circumferential seats in the interior of each blade socket and on the exterior of each blade shank. It will be noted from Figs. 1 and 2 that the grooves in the blades are somewhat elongated in cross-section, the arrangement being such that if the blades are moved radially inwardly from their operative positions the bearing balls may be in serted through holes 44, 48 and 48 into the grooves and thereafter-the blades may be restored to their operative positions as in Fig. 1. After the balls have been inserted the holes are closed by screw plugs 50 to prevent entry of dirt and to retain lubricant. No holes have been provided for the bottom row of balls 42 since the balls of this row may be inserted from the inside of the hub. The movement of the blades from the inward position in which the balls are inserted to the outward position in which they are retained in operative position is controlled by a wedge arrangement indicated at 52 in Fig. 1 and particularly illustrated in Fig. 3, the detailed construction and operation of which will later appear.

Each servo-motor comprises an outer rotatable sleeve-like member 54 (Fig. 5) and an inner member 65, the outer member 54 having two diametrically opposed inwardly projecting vanes 56 and 58 and the inner member 65 having two diametrically opposed outwardly projecting abutments 62 and 64 of the same length as 56 and 58, the difference between the external diameter of the inner member and the inner diameter of the outward member being the depth of the .vanes and abutments. The outer rotatable sleevelike member 54 is provided with means such as splines 84 to prevent motion relative to the blade 30, and the inner member 65 has similar means 66 (Fig. l) for preventing motion relative to stationary member 80.

Stationary member is provided with an outwardly extended radial flange 6| (Fig. 1). The outer member 54 has a shoulder 63 forming a recess extending somewhat beyond the depth of vanes 56 and 58 and in line with the ends of the vanes which surround flange iii. A cap 68 is screwed on to the outer end of member 60 until it bears against the end of abutments 56, 58, 62 and 64, entering a circular recess 69 countersunk in the outer end of member 54 and extending somewhat beyond the depth of the vanes 56 and 58 in line with the outer ends of these vanes. After cap 68 has been screwed to position a retaining pin 10 is inserted to lock it. In this position, close contact is made between the ends of member 85 and 84 thus closing the ends of the cavities formed by the assembled position of these meizgbers. Flange 6i and cap 68 extend radially somewhat beyond the depth of vanes 58 and 88 to provide a fluid seal between abutments 82 and 84 and the wall portion of outer member 84. Flange Si is provided in its periphery with a ring groove in which is a sealing ring 12. A similar ring I4 is provided around cap 88. The ring grooves are extended in depth, in reduced form, beyond the inner circumference of the rings, as indicated at 18 and 18 (Figs. 1 and 2) to provide relatively thin annular fln-llke flange portions of each member 8I and 88 in contact with the corresponding ends of member 84 and disposed between the ends of the outer member 84 and the corresponding sealing rings '12 and I4. The purpose of these flexible flange portions is to maintain constant contact with the ends of the vanes. As the sealing rings prevent external leakage of the assembly at this point, any fluid passing the shoulders into the recesses creates sufficient pressure for proper seating of the flnlike flange portions on the end of the vanes.

After the elements 80. 85. '84 and 8-8 have been assembled as indicated above and tested, the motor is installed as a unit in the hollow end of the blade. Preferably the outside dimensions of the motor and the inside dimensions of the blade are such as to provide a push flt between the outer member 54 and the blade to secure the motor flrmly in the blade ends and insure its remaining in proper alignment with the blades. In the embodiment illustrated the outer surface of the motor contacts the inner surface of the blade at two spaced locations 80 and 82 and the blade torque is transmitted from the outer member 54 of the motor to the blade through a serrated or splined connection 84 (Fig. 2).

The bottom portion of outer member 54 is provided with an outwardly projecting annular flange 88 which underlies the root end of blade 80 and has, on a portion of its circumference, a. gear sector 88 the teeth of which mesh with the teeth of a blade synchronizing gear 90 rotatably mounted in a ball bearing 9| in hub member I0. The cooperation of. the beveled gear sector 88 of each motor and the blade bevel gear 90 insures simultaneous and similar pitch changes of all blades.

Slight adjacents in pitch between the several blades to obtain a condition of aerodynamic balance may be accomplished manually by utilizing the adjustable feature, indicated at 82, of the gear 80 (Fig. 1). Gear 90 has three separate segments each one of which meshes with one of the motor gear segments, the segments of the gear 90 being secured to a continuous inner or hub portion 04 thereof by a spline connection arranged to provide a vernier adjustment between the separate sectors and the continuous hub portion. This adjustable feature is particularly illustrated and described in United States application Serial No. 361,565, filed October 17, 1940, by John E. Anderson, for Blade Adjusting Means, and assigned to the assignee of this application, and which issued as Patent No. 2,396,- 630 on March 19, 1946.

The bottom of inner member 80 is provided with a pair of diametrically opposed partly cylindrical lugs 88 and 88 (Fig. 6). and is also provided with four circular sockets, two of which are indicated at I02 and I04 in Fig. 4, which receive the tubular flanged connectors I08, I08, I I and H2. As is shown in Fig. 4 each of these 4 connectors is provided intermediate its length with an outwardly extending flange, and has reduced diameter end portions received in corresponding wells or recesses in the bottom of the inner motor member 60 and in the hub member I0. Depressions I00 reduce weight of member 80.

When the blade and motor are installed in the propeller hub the blade and motor combination is brought to a position in which lugs 88 and 98 have their center line in a plane perpendicular to the axis of shaft I2. In this position the lugs will flt into cylindrical recesses IIS provided in hub I0, and the corresponding lugs of adjacent blades will be brought into close proximity between' each pair of adjacent sockets. The surface of each lug facing an adjacent lug is flattened, as indicated at I I4 and I I8 (Figs. 2 and 6) and these flats bear against the ends of slidable blocks shown atII8 and I20 in Figs. 2 and 3. For convenience in assembly a strap I I9 (Figs. 2 and 3) is placed, as shown, in grooves in the sides of each pair of blocks '8, I20. Between blocks H8 and I20 there is a wedge I22 adjustable by means .of a nut I24 threaded into the hub and locked in adjusted position by nut I26 on the stem of the wedge member. When lugs 98 and 88 are positioned as indicated above, the ends of connectors I08, I08, H0 and H2 (Fig. 6) projecting from the bottom of the member are received in corresponding sockets provided in the portion of the hub member covered by the bottom end of the motor member 80, two of these sockets being indicated at I28 and I80 in Fig. 4. As is also indicated in Fig. 4, the reduced end of each connector is surrounded by a flexible packing I82 expanded in position between the connector and the wall of the socket. This packing is held in relation to the connector by the compression spring I34. Preferably the sockets in the hub member are of sufficient size to just receive the flanges on the connector members.

when the blade-motor combination is inserted in its blade socket, wedge I22 is retracted, permitting blocks 8 and I20 to move toward each other and permitting the blade and motor combination to move inwardly beyond its normal operating position in the blade socket. When this occurs connectors I08, I08, H0 and H2 will be forced into the corresponding sockets in the hub member, the flanges of the connectors compressing springs I84. With the blade and motor combination in this position the bearing balls are inserted in the corresponding race grooves, after which wedge members I22 are forced in by nut I24, forcing the blade-motor combinations radially outwardlyuntil each blade bearing is given the desired preloading to maintain the blade in flrm association with its corresponding socket. When this occurs, springs I34 force the packings and connectors outwardly and maintain the fluid seals. In addition to serving as abutments for preloading the blade retaining bearings. lugs 88 and 88 also serve to prevent rotation of the inner portion of the motor and thereby resist the torque reaction during the pitch changing movements of the motor.

Fluid may be supplied by a pump I88 as diagrammatically illustrated in Fig. 1, and the connection of the pump outlet with either side of the motor and the connection of the opposite side of the motor with the sump I38 may be controlled by a speed responsive device such as a governor indicated at I40. Two fluid lines I42 and I44, which may be alternatively pressure or drain lines depending upon the direction of pitch change required, are led through a suitable transfer bearing I48 (Fig. 1) to a pair of channels I48 and I50 connected with manifolds I52 and I54.

While a suitable hydraulic system for supplying pressure fluid to and draining exhaust fluid from the motors has been diagrammatically illustrated, it is to be understood that the invention is in no way limited to any particular system but that various other hydraulic systems may be used such, for example, as that particularly illustrated and described in co-pending United States application Serial No. 422,25 flled December 9, 1941, by Donald W. Perin and Nelson R. Richmond, for Propeller Control Means, and assigned to the assignee of this application, and now abandoned, in which the source of fluid under pressure is a pump carried by and rotatablewith the propeller hub and in which a fluid distribution valve is disposed in the propeller hub and hydraulically interposed between this pump and the pitch changing motors.

As explained above, and as particularly illustrated in Fig. 6, there are four connectors associated with each pitch changing motor, two being connected with one side of the motor and the other two with the opposite side of the motor. For example, connectors I08 and H0 are connected with one side of the motor through channels I56, I48 (Figs. 1 and 6), while connectors I06 and I I2 are connected with the opposite side of the motor through the channels I64, I66, I68, I and I12. Thus for each motor there is one pair of connectors associated with one side of the motor and another pair associated with the opposite side. One of the manifolds I52 or I54 is connected with all passages in the hub member associated with one pair of connectors and the other manifold is connected with the other pairs of connectors. By referring to Figs. 4 and 6 it may be seen that the passages include channels, as indicated at I14, connecting adjacent hub member sockets in the same plane at right angles to the axis of rotation of the hub, and fluid channels in the inner motor member connecting the sockets of each pair together and with the motor chambers. It will be noticed that some fluid channels, such as I 62, I12 are annular grooves out in the outer surface of inner member 60 within sleeve 54.

In order to prevent leakage of fluid past the various motor vanes and abutments, their surfaces are covered by flexible packing formed of resilient material indicated at I16 in Fig. 5, and each packing member is held in place by a generally cup shaped washer member as indicated at I18. The washer members for abutments 62 and G4 are held in place by rivets I80 while each washer member for vanes 56 and 58 is held in place by a rivet I82 extending through member 54.

In the modified form of the device shown in Fig. 7 the wedge members particularly indicated at II8, I20 and I22 in Figs. 2 and 3 are omitted and the hub member I0 within each blade socket 24 is provided with an internally screw threaded boss I86 coaxial with the blade socket. The inner member 60' of the vane motor is internally threaded to receive a hollow plug I88 having a lower end surface adapted to contact the outer surface of the boss I86, and provided in its lower end with a wrench socket I90.

The blade retention bearings may be preloaded by manipulation of the plug I88 in the following manner.

Before a blade is inserted in a blade socket the III plug member I88 is inserted in the end of the center post and screwed upwardly. as viewed in Figure '7, to a position which will permit the base end of the blade to move into the socket to the maximum extent, at which position of the blade the balls may be inserted as previoushr described. After the balls have all been inserted, a wrench is inserted through boss I88 into socket I90 ln-plug I88 and this plug is screweddown, as viewed in Figure 7, to force the blade upwardly in the blade socket, the incidental reaction being taken by pressure of the end of plug I88 on boss I86. Holes I89 are provided in the plug I88 to receive a lock pin (not shown) for preventing accidental movement of the plug after it has once been.adjusted. After plug member I88 has been moved a sumcient distance to apply the proper preloading to the blade bearings a plug I92 is screwed into the hole in boss I86 to prevent passage of lubricating fluid to the interior of the shaft-surrounding portion of hub member I0. a

In this modified form of the invention it is to be noted that instead of the integral fin-like flange portions particularly illustrated in Figs. 1 and 4, separate washers, one of which is indicated at I94, are used to seal the ends of the vane motor. Any fluid passing the shou ders into the recess I95 creates sufficient pressure for proper seating of the separate ring on the end of the vanes. The seal ring 12 is retained in this modification and an additional endless thrust ring I98 is added providing a centering action for the internal parts and also having the function of retaining the seal ring 12 in position for assembly. After rings I94 and 12 are assembled in position ring I96 is slipped over ring 12 and left in position to compress this ring into the annular groove provided for it in the periphery of washer I94. Then as the outer member 54 of the motor is brought to assembled position ring I96 is moved down to the position illustrated in Fig. 7 and ring 12 is he'd in operative position by the circumferential lower end of member 54, ring I96 being forced down into a peripheral recess provided for it in the lower flange portion of the inner member 60 and resting against an annular shoulder at the bottom of this recess.

It will be appreciated from the above that the fluid motor is complete in itself and may be assembled and tested as a unit entirely independently of the hub-blade assembly.

While a suitable mechanical embodiment has been hereinabove described and illustrated in the accompanying drawings for the purpose of disclosing the invention, it is to be understood that the invention is not limited to the particular embodiment so illustrated and described, but that such changes in the size, shape and arrangement of the various parts may be resorted to as come within the scope of the sub-joined claims.

Having now described the invention so that others skilled in the art may clearly understand the same, what it is desired to secure by Letters Patent is as follows:

1. In a controllable-pitch propeller, a hub having a plurality of blade receiving sockets, a blade in each socket, an anti-friction bearing retaining each blade in its socket against outwardly directed forces, a fluid motor in the socket-received end of each bade, a pair of diametrically opposed lugs on each motor, wedge members, and means for forcing said wedge members between adjacent lugs of adjacent motors, for supporting 7 said motors and said blades against inwardly directed forces.

2. In a controllable-pitch propeller having a hub with a plurality of blade-receiving sockets, a hollow end blade in each socket, a thrust bearin in each socket for retaining its blade in operative association with said hub, an individual motor for rotating each blade in pitch changing directions, each motor comprising an inner member, and a hollow outer member fixed in the hollow root end of a blade and rotatable about said inner member, adjacent portions of adjacent inner members being closely spaced from each other circumferentially of said hub, and manually adjustable means operable to exert a separating force on and located between said closely spaced adjacent portions for controlling the pre-loading of said thrust bearings.

3. In a propeller, a rotary driving element having blade shank receiving sockets formed therein, a blade mounted in each of said sockets, each of said b ades being provided with a flange adjacent the shank end thereof, means fixed at a predetermined distance from the axis of said rotary driving element and cooperating with the flanges for blocking outward displacement of the blades from the sockets, and means interposed between the inner ends of said blade shanks for pressing the blade shanks radially outwardly, said last mentioned means including a part engaging the inner end of one blade shank, a part engaging the inner end of another blade shank, means for adjusting said parts relative to each other to vary the pressure exerted thereby on the inner ends of said b ades, and means for fixing said parts in their adjusted positions.

4. In combination with a controllable-pitch propeller having a plurality of blades and a blade retaining hub, means retaining said blades in said hub, individual motors for rotating said blades in pitch changing directions, each motor comprising an outer member and an inner member, said outer member being fixed in the hollow root end of a blade and rotatable about said inner member, said inner member being separate from said hub and movable in a direction longitudinally of said blade, means fixed with respect to said hub, said inner member having diametri-, cally opposed elements, movable with said inner member into operative engagement with said means fixed with respect to said hub, for preventing rotation of said inner member relative to said hub, said outer member having means holding said diametrically opposed elements in operative relation with said means fixed with respect to said hub.

5. A device as claimed in claim 3 in which the adjusting means comprises relatively movable screw threaded members.

6. A device as claimed in claim 5 in which at least one of the screw threaded members is accessible for movement relative to the other screw threaded member after the blade and the rotary driving element have been assembled.

'7. An adjustable variable pitch propeller'comprising a rotary driving element having blade shank receiving sockets fomed therein, a blade rotatably mounted in each of said sockets, cooperating means on said blade shank and said hub for limiting outward movement of each of said blades in the socket in which it is rotatably mounted, means interposed between the inner ends of said blade shanks for pressing said blade shanks radially outwardly, said last mentioned means including cooperating elements adjustable I relative to each other to vary the pressure exerted by said means on the inner ends of said blades, and means for fixing said elements in their adjusted positions.

8. In a controllable pitch propeller having a hub with a plurality of blade receiving sockets, a hollow end blade in each socket, a thrust bearing in each socket for retainingits blade in operative association with said hub, an individual motor for rotating each blade in pitch changing directions, each motor comprising an inner member, and an outer member fixed in the hollow root end of a blade and rotatable about said inner member, means fixed with respect to said hub, said inner member being separate from said hub and movable radially of the hub while supported in a blade receiving socket and having diametrically opposed lugs operatively engaging said means fixed with respect to said hub for preventing rotation of said inner member relative to said hub, each lug being close to a corresponding lug on the next adjacent motor, and manually adjustable means operable through said lugs to force said inner member, outer member and blade end toward said thrust bearing for controlling the preloading on said thrust bearings.

9. The invention set forth in claim 8 in which said manually adjustable means comprises wedges, each operable between a pair of closely adjacent lugs to separate the same.

10. In a controllable-pitch propeller having a hub with a plurality of blade-receiving sockets, a blade in each socket, means for fixing said blades against radial movement including meansfixed with respect to said hub for retaining said blade in said socket, and manually operable means within said hub manually operable while said hub and blades are assembled for moving said blades outwardly in said sockets against said fixed means.

11. In a controllable-pitch propeller having a hub with a plurality of blade-receiving sockets, a blade in each socket, means for fixing said blades against radial movement including means fixed with respect to said hub for retaining said blade in said socket, and manually operable means within said hub between two adjacent blades acting on one blade and reacting on the other blade and including means exerting a separating force on said adjacent blades and forcing said blades outwardly in said sockets against said fixed means.

12. In a controllable-pitch propeller having a hub with a plurality of blade-receiving sockets, a blade in each socket, means for fixing said blades against radial movement including means fixed with respect to said hub for retaining said blade in said socket, and a manually adjustable wedging device within said hub and between said blades and means for moving said device between said blades to act on one blade and react on another blade and wedge said blades outwardly in said sockets against said fixed means.

JOHN E. ANDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,116,974 Bergesen Nov. 10, 1914 1,365,132 Vessey Jan. 11', 1921 (Other references on following page) 9 UNITED STATES PATENTS Number Name Date Pescara Jan. 17, 1922 Wood Aug. 14, 1928 Cook, Jr. Apr. 21, 1931 Blanchard July 26, 1932 Fee Aug. 1, 1933 Hebbard May 8, 1934 Bace Sept. 10, 1935 Sandberg Feb. 9, 1937 Manning Feb. 7, 1939 Barish Feb. 14, 1939 Chilton May 6, 1941 Humphrey June 10, 1941 Martin et a1 Sept. 22, 1942 Number Number 

